Glossary

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| Adipose                   | The body's fat stores or fatty layers.                             |
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| Aeroallergens             | Airborne allergens.                                                |
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| Aerosolized Dust          | Dust which is disturbed and placed into airborne suspension.       |
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| Ambient Air               | Surrounding air; used to refer to outside air.                     |
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| Antagonism                | Occurs in toxicology when the effect of one chemical               |
|                           | suppresses the negative effect of another (i.e., calcium tends     |
|                           | to reduce the toxic effect of cadmium).                            |
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| Apportionment             | Attribution of a portion, based on Arizona's share of the          |
|                           | national population.                                               |
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| -cide                     | Any substance used to kill a family of agents (e.g., fungi,        |
|                           | insects).                                                          |
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| Carbon Monoxide (CO)      | A gas formed as a by-product of inefficient combustion,            |
|                           | especially caused by automobile exhaust.  Symptoms of low-         |
|                           | level CO exposure include headaches and dizziness; these           |
|                           | symptoms are reversible.                                           |
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| Carcinogens               | Substances that may cause cancer.                                  |
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| Clinical v. Subclinical   | Refers to the recognizability of disease: clinically apparent      |
| Disease                   | disease can be detected by means of a physical exam;               |
|                           | subclinical disease is detectable only through laboratory          |
|                           | tests.                                                             |
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| Coliform Standard         | Coliform bacteria generally do not cause disease, but the          |
|                           | presence of coliforms in water indicate that conditions are        |
|                           | conducive for survival of bacteria.  The presence of fecal         |
|                           | coliform indicates contamination from human feces and an           |
|                           | increased risk for transmission of waterborne diseases.            |
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| Confounding Factors       | Factors which mask or confuse the effects of another factor        |
|                           | (e.g., cigarette smoking is a greater cause of cancer than         |
|                           | asbestos and overwhelms the number of cancers caused by            |
|                           | asbestos).                                                         |
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| Dosimetry                 | Measure of the dose radiation.                                     |
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| Dross                     | Leftover slag after metal is burned.                               |
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| Epidemiology              | The study of the distribution and causes of disease and            |
|                           | epidemics.                                                         |
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| Fungicides                | Chemicals used to kill fungi.                                      |
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| Hantavirus                | A virus carried by rodents, especially the deer mouse is the       |
|                           | southwestern U.S.; this virus causes a severe respiratory          |
|                           | infection.                                                         |
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| Herbicides                | Chemicals used to kill plants.  Most herbicides are selective,     |
|                           | meaning that they only kill certain types of plants.               |
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| Insecticide               | Chemicals used to kill insects.                                    |
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| Ionizing Radiation        | Atoms or molecules that lose or gain electrons, making them        |
|                           | radioactive.                                                       |
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| Melanoma                  | A type of skin cancer.                                             |
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| Methemoglobinemia         | A type of blue-baby syndrome that can lead to death in             |
|                           | infants.                                                           |
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| Mutagen                   | A substance that changes (or mutates) the DNA.                     |
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| Myeloma                   | A cancer of the bone marrow.                                       |
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| Natural Background        | Exposure to a pollutant that would occur in the absence of         |
|                           | human activities.                                                  |
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| Nematocide                | Pesticide that controls nematodes (round worms).                   |
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| Neurotoxicity             | Damage to the nervous system (brain or peripheral nerves).         |
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| Nitrogen Oxides           | Nitrogen oxides react with ozone in the atmosphere to form         |
|                           | photochemical smog.                                                |
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| Order of Magnitude        | Factor of ten.  An "order of magnitude" estimate implies very      |
|                           | high uncertainty (e.g., one is confident of the estimate within    |
|                           | a factor of ten).                                                  |
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| Ozone (O3)                | A secondary pollutant that is formed by the reaction of            |
|                           | nitrous oxides and certain organic compounds in air, a key         |
|                           | ingredient of photochemical smog.  High levels of ozone in         |
|                           | urban environments are generally associated with high              |
|                           | automobile traffic.  Ozone causes eye irritation, coughing         |
|                           | and related symptoms in humans, while it reduces the               |
|                           | growth of sensitive plants.                                        |
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| Pesticides                | Chemicals used to kill pests; common pesticides include            |
|                           | herbicides, insecticides, and fungicides.                          |
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| Photochemical Smog        | A mixture of chemicals in the atmosphere that is formed by         |
|                           | the reaction of sunlight and primary air pollutants.  Ozone        |
|                           | and PAN (peroxyacetyl nitrate) are two main ingredients of         |
|                           | photochemical smog.  Coughing, eye irritation, shortness of        |
|                           | breath, and headache are symptoms of photochemical                 |
|                           | smog.                                                              |
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| PM-10                     | Particulate matter (particles) suspended in air less than ten      |
|                           | microns in size.  These very small particles have more             |
|                           | serious health consequences than large particles because           |
|                           | the smaller particles move deeper into the respiratory             |
|                           | system.                                                            |
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| Potency Factor            | Indicates the potency of a chemical carcinogen with respect        |
|                           | to its tendency to cause cancer.                                   |
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| Radiochemical             | Chemical or drug that is radioactive.                              |
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| Sulfur Dioxide (SO2)      | A gas produced during the combustion of fuels containing           |
|                           | sulfur, especially emitted from coal-burning power plants          |
|                           | and, to a lesser extent, from metal refining.  At higher levels,   |
|                           | sulfur dioxide causes coughing and eye irritation.  It is the      |
|                           | main ingredient of acid rain.                                      |
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| Synergism                 | Occurs in toxicology when two chemicals produce an effect          |
|                           | worse than would occur if the effect of the two chemicals          |
|                           | were simply added together.  It is the opposite of                 |
|                           | antagonism.                                                        |
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| Teratogen                 | A substance that causes a birth defect.                            |
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| Threshold                 | A dose of a chemical or radiation below which no toxicity          |
|                           | occurs.  Until recently, toxicologists regarded cancer-causing     |
|                           | chemicals as having a "zero threshold," meaning that even a        |
|                           | small dose results in some cancer risk.  The zero threshold        |
|                           | model has been widely criticized in recent years, and the          |
|                           | uncertainty regarding the effect of very low exposures to          |
|                           | carcinogens is very high.                                          |
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| Turbidity                 | A measure of the clarity of water: water with high turbidity       |
|                           | appears murky; low turbidity indicates clear water.                |
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| Valley Fever              | A fungus disease prevalent in the desert southwest.                |
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| Vector                    | An organism that carries pathogens from one host to                |
|                           | another.                                                           |
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| Weight-of-Evidence        | In decision making, this approach is used to show which side       |
| Approach                  | of an argument is more strongly supported.  This is a lower        |
|                           | level of evidence than is used in a jury trial, in which the       |
|                           | argument (that someone is guilty of a crime) must be proven        |
|                           | "beyond a reasonable doubt."                                       |
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| Zoonotic                  | A disease of humans acquired from an animal source (e.g.           |
|                           | rabies).                                                           |
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